Republican presidential candidate Donald Trump is "uninformed" and an unfit leader, according to his competition Jeb Bush.

Republican front runner Donald Trump is “uninformed” and the prospect of him as commander-in-chief is “kind of scary,” rival Jeb Bush said Sunday.

“I have great doubts about Donald Trump’s ability to be commander-in-chief. I really do,” Bush said on CBS’s “Face the Nation.” “If you listen to him talk, it’s kind of scary, to be honest with you, because he’s not a serious candidate.”

The former Florida governor derided Trump’s call for a registry of Muslims in the U.S., and claimed the brash billionaire has taken contradictory positions on Syria.

“In these really serious times, he’s not a serious leader,” Bush said. “He's all over the map, misinformed at best, and preying on people’s fear at worst.”

Bush repeated his position that any Republican would be a better president than Hillary Clinton, but said he’d let voters decide whether that should apply to Trump.

Trump mocked New York Times reporter Serge Kovaleski, flailing his arms in apparent imitation of the journalist, who has a congenital condition that limits joint movement. Trump later insisted he didn’t know what Kovaleski looks like, though the two have met many times.

Bush said in an interview on Sunday that he had “great doubts” about Trump’s ability to legitimately run the country.

(Gretchen Ertl/REUTERS)

“This is the pattern, isn’t it? The pattern is — he says something insulting, offensive and outrageous; the media pays attention; then he claims we all misunderstood him,” Fiorina said on “Fox News Sunday.” “This is the pattern, perhaps, of an entertainer. It’s certainly not the pattern of a leader.”

Ohio Gov. John Kasich agreed, declining to say whether he’d support Trump if the businessman were nominated.

“I think he’s very divisive and I do not believe he will last,” he said on ABC’s “This Week.”

“Somebody who divides this country, here in the 21st century, who’s calling names of women and Muslims and Hispanics and mocking reporters, and says, ‘I didn’t do it,’ but he did do it — it’s just not going to happen,” Kasich said.